Refactor calling convention settings. (#304)

Add a calling-convention setting to the `Flags` used as part of the
`TargetIsa`. This allows Cretonne code that generates calls to use the
correct convention, such as when emitting libcalls during legalization
or when the wasm frontend is decoding functions. This setting can be
overridden per-function.

This also adds "fast", "cold", and "fastcall" conventions, with "fast"
as the new default. Note that "fast" and "cold" are not intended to be
ABI-compatible across Cretonne versions.

This will also ensure Windows users will get an `unimplemented!` rather
than silent calling-convention mismatches, which reflects the fact that
Windows calling conventions are not yet implemented.

This also renames SpiderWASM, which isn't camel-case, to Baldrdash,
which is, and which is also a more relevant name.

cranelift/filetests/parser/branch.cton

@@ -9,7 +9,7 @@ ebb0:
 ebb1:
     jump ebb0()
 }
-; sameln: function %minimal() system_v {
+; sameln: function %minimal() fast {
 ; nextln: ebb0:
 ; nextln:     jump ebb1
 ; nextln: 
@@ -25,7 +25,7 @@ ebb0(v90: i32):
 ebb1(v91: i32):
     jump ebb0(v91)
 }
-; sameln: function %onearg(i32) system_v {
+; sameln: function %onearg(i32) fast {
 ; nextln: ebb0(v90: i32):
 ; nextln:     jump ebb1(v90)
 ; nextln: 
@@ -41,7 +41,7 @@ ebb0(v90: i32, v91: f32):
 ebb1(v92: i32, v93: f32):
     jump ebb0(v92, v93)
 }
-; sameln: function %twoargs(i32, f32) system_v {
+; sameln: function %twoargs(i32, f32) fast {
 ; nextln: ebb0(v90: i32, v91: f32):
 ; nextln:     jump ebb1(v90, v91)
 ; nextln: 
@@ -57,7 +57,7 @@ ebb0(v90: i32):
 ebb1:
     brnz v90, ebb1()
 }
-; sameln: function %minimal(i32) system_v {
+; sameln: function %minimal(i32) fast {
 ; nextln: ebb0(v90: i32):
 ; nextln:     brz v90, ebb1
 ; nextln: 
@@ -72,7 +72,7 @@ ebb0(v90: i32, v91: f32):
 ebb1(v92: i32, v93: f32):
     brnz v90, ebb0(v92, v93)
 }
-; sameln: function %twoargs(i32, f32) system_v {
+; sameln: function %twoargs(i32, f32) fast {
 ; nextln: ebb0(v90: i32, v91: f32):
 ; nextln:     brz v90, ebb1(v90, v91)
 ; nextln: 
@@ -94,7 +94,7 @@ ebb30:
 ebb40:
     trap user4
 }
-; sameln: function %jumptable(i32) system_v {
+; sameln: function %jumptable(i32) fast {
 ; check:      jt2 = jump_table 0, 0, ebb10, ebb40, ebb20, ebb30
 ; check:      jt200 = jump_table 0
 ; check:  ebb10(v3: i32):

cranelift/filetests/parser/call.cton

@@ -5,18 +5,18 @@ function %mini() {
 ebb1:
     return
 }
-; sameln: function %mini() system_v {
+; sameln: function %mini() fast {
 ; nextln: ebb1:
 ; nextln:     return
 ; nextln: }
 
-function %r1() -> i32, f32 spiderwasm {
+function %r1() -> i32, f32 baldrdash {
 ebb1:
     v1 = iconst.i32 3
     v2 = f32const 0.0
     return v1, v2
 }
-; sameln: function %r1() -> i32, f32 spiderwasm {
+; sameln: function %r1() -> i32, f32 baldrdash {
 ; nextln: ebb1:
 ; nextln:     v1 = iconst.i32 3
 ; nextln:     v2 = f32const 0.0
@@ -25,14 +25,14 @@ ebb1:
 
 function %signatures() {
     sig10 = ()
-    sig11 = (i32, f64) -> i32, b1 spiderwasm
+    sig11 = (i32, f64) -> i32, b1 baldrdash
     fn5 = %foo sig11
     fn8 = %bar(i32) -> b1
 }
-; sameln: function %signatures() system_v {
-; check:      sig10 = () system_v
-; check:      sig11 = (i32, f64) -> i32, b1 spiderwasm
-; check:      sig12 = (i32) -> b1 system_v
+; sameln: function %signatures() fast {
+; check:      sig10 = () fast
+; check:      sig11 = (i32, f64) -> i32, b1 baldrdash
+; check:      sig12 = (i32) -> b1 fast
 ; not:        fn0
 ; check:      fn5 = %foo sig11
 ; check:      fn8 = %bar sig12
@@ -88,7 +88,7 @@ function %special1(i32 sret, i32 fp, i32 csr, i32 link) -> i32 link, i32 fp, i32
 ebb0(v1: i32, v2: i32, v3: i32, v4: i32):
     return v4, v2, v3, v1
 }
-; check: function %special1(i32 sret, i32 fp, i32 csr, i32 link) -> i32 link, i32 fp, i32 csr, i32 sret system_v {
+; check: function %special1(i32 sret, i32 fp, i32 csr, i32 link) -> i32 link, i32 fp, i32 csr, i32 sret fast {
 ; check: ebb0(v1: i32, v2: i32, v3: i32, v4: i32):
 ; check:     return v4, v2, v3, v1
 ; check: }

cranelift/filetests/parser/instruction_encoding.cton

@@ -13,7 +13,7 @@ ebb1(v0: i32 [%x8], v1: i32):
 @55 v9 = iadd v8, v7
 @a5 [Iret#5] return v0, v8
 }
-; sameln: function %foo(i32, i32) system_v {
+; sameln: function %foo(i32, i32) fast {
 ; nextln: ebb1(v0: i32 [%x8], v1: i32):
 ; nextln:     [-,-]$WS v2 = iadd v0, v1
 ; nextln:     [-]$WS trap heap_oob

cranelift/filetests/parser/keywords.cton

@@ -2,4 +2,4 @@ test cat
 
 ; 'function' is not a keyword, and can be used as the name of a function too.
 function %function() {}
-; check: function %function() system_v
+; check: function %function() fast

cranelift/filetests/parser/rewrite.cton

@@ -9,7 +9,7 @@ ebb100(v20: i32):
     v9200 = f64const 0x4.0p0
     trap user4
 }
-; sameln: function %defs() system_v {
+; sameln: function %defs() fast {
 ; nextln: ebb100(v20: i32):
 ; nextln:     v1000 = iconst.i32x8 5
 ; nextln:     v9200 = f64const 0x1.0000000000000p2
@@ -23,7 +23,7 @@ ebb100(v20: i32):
     v200 = iadd v20, v1000
     jump ebb100(v1000)
 }
-; sameln: function %use_value() system_v {
+; sameln: function %use_value() fast {
 ; nextln: ebb100(v20: i32):
 ; nextln:     v1000 = iadd_imm v20, 5
 ; nextln:     v200 = iadd v20, v1000

cranelift/filetests/parser/tiny.cton

@@ -5,7 +5,7 @@ function %minimal() {
 ebb0:
     trap user0
 }
-; sameln: function %minimal() system_v {
+; sameln: function %minimal() fast {
 ; nextln: ebb0:
 ; nextln:     trap user0
 ; nextln: }
@@ -18,7 +18,7 @@ ebb0:
     v1 = iconst.i8 6
     v2 = ishl v0, v1
 }
-; sameln: function %ivalues() system_v {
+; sameln: function %ivalues() fast {
 ; nextln: ebb0:
 ; nextln:     v0 = iconst.i32 2
 ; nextln:     v1 = iconst.i8 6
@@ -34,7 +34,7 @@ ebb0:
     v2 = bextend.b32 v1
     v3 = bxor v0, v2
 }
-; sameln: function %bvalues() system_v {
+; sameln: function %bvalues() fast {
 ; nextln: ebb0:
 ; nextln:     v0 = bconst.b32 true
 ; nextln:     v1 = bconst.b8 false
@@ -47,7 +47,7 @@ function %select() {
 ebb0(v90: i32, v91: i32, v92: b1):
     v0 = select v92, v90, v91
 }
-; sameln: function %select() system_v {
+; sameln: function %select() fast {
 ; nextln: ebb0(v90: i32, v91: i32, v92: b1):
 ; nextln:     v0 = select v92, v90, v91
 ; nextln: }
@@ -69,7 +69,7 @@ ebb0:
     v1 = extractlane v0, 3
     v2 = insertlane v0, 1, v1
 }
-; sameln: function %lanes() system_v {
+; sameln: function %lanes() fast {
 ; nextln: ebb0:
 ; nextln:     v0 = iconst.i32x4 2
 ; nextln:     v1 = extractlane v0, 3
@@ -85,7 +85,7 @@ ebb0(v90: i32, v91: i32):
     v3 = irsub_imm v91, 45
     br_icmp eq v90, v91, ebb0(v91, v90)
 }
-; sameln: function %icmp(i32, i32) system_v {
+; sameln: function %icmp(i32, i32) fast {
 ; nextln: ebb0(v90: i32, v91: i32):
 ; nextln:     v0 = icmp eq v90, v91
 ; nextln:     v1 = icmp ult v90, v91
@@ -101,7 +101,7 @@ ebb0(v90: f32, v91: f32):
     v1 = fcmp uno v90, v91
     v2 = fcmp lt v90, v91
 }
-; sameln: function %fcmp(f32, f32) system_v {
+; sameln: function %fcmp(f32, f32) fast {
 ; nextln: ebb0(v90: f32, v91: f32):
 ; nextln:     v0 = fcmp eq v90, v91
 ; nextln:     v1 = fcmp uno v90, v91
@@ -115,7 +115,7 @@ ebb0(v90: i32, v91: f32):
     v0 = bitcast.i8x4 v90
     v1 = bitcast.i32 v91
 }
-; sameln: function %bitcast(i32, f32) system_v {
+; sameln: function %bitcast(i32, f32) fast {
 ; nextln: ebb0(v90: i32, v91: f32):
 ; nextln:     v0 = bitcast.i8x4 v90
 ; nextln:     v1 = bitcast.i32 v91
@@ -135,7 +135,7 @@ ebb0:
     stack_store v1, ss10+2
     stack_store v2, ss2
 }
-; sameln: function %stack() system_v {
+; sameln: function %stack() fast {
 ; check:     ss2 = explicit_slot 4
 ; check:     ss3 = incoming_arg 4, offset 8
 ; check:     ss4 = outgoing_arg 4
@@ -162,7 +162,7 @@ ebb0(v1: i32):
     store aligned v3, v1+12
     store notrap aligned v3, v1-12
 }
-; sameln: function %memory(i32) system_v {
+; sameln: function %memory(i32) fast {
 ; nextln: ebb0(v1: i32):
 ; nextln:     v2 = load.i64 v1
 ; nextln:     v3 = load.i64 aligned v1
@@ -187,7 +187,7 @@ ebb0(v1: i32):
     regfill v1, ss0 -> %10
     return
 }
-; sameln: function %diversion(i32) system_v {
+; sameln: function %diversion(i32) fast {
 ; nextln:     ss0 = spill_slot 4
 ; check: ebb0(v1: i32):
 ; nextln:     regmove v1, %10 -> %20
@@ -204,7 +204,7 @@ ebb0:
     copy_special %20 -> %10
     return
 }
-; sameln: function %copy_special() system_v {
+; sameln: function %copy_special() fast {
 ; nextln: ebb0:
 ; nextln:     copy_special %10 -> %20
 ; nextln:     copy_special %20 -> %10